Resources

1. Medical Use

Pain is the main reason people ask for a prescription, says Barth Wilsey, MD, a pain medicine specialist at the University of California Davis Medical Center. It could be from headaches, a disease like cancer, or a long-term condition, like glaucoma or nerve pain.

If you live in a state where medical marijuana is legal and your doctor thinks it would help, you’ll get a “marijuana card.” You will be put on a list that allows you to buy marijuana from an authorized seller, called a dispensary.

Doctors also may prescribe medical marijuana to treat:

* Muscle spasms caused by multiple sclerosis

* Nausea from cancer chemotherapy

* Poor appetite and weight loss caused by chronic illness, such as HIV, or nerve pain

* Seizure disorders

* Crohn's disease

The FDA has also approved THC, a key ingredient in marijuana, to treat nausea and improve appetite. It's available by prescription Marinol (dronabinol) and Cesamet (nabilone).

Continue reading below...

How Does It Work?

Your body already makes marijuana-like chemicals that affect pain, inflammation, and many other processes. Marijuana can sometimes help those natural chemicals work better, says Laura Borgelt, PharmD, of the University of Colorado.    

How Is It Used?

Medical marijuana may be:

* Smoked

* Vaporized (heated until active ingredients are released, but no smoke is formed)

* Eaten (usually in the form of cookies or candy)

* Taken as a liquid extract 

Cannabis has been used to reduce nausea and vomiting in chemotherapy and people with AIDS, and to treat pain and muscle spasticity; its use for other medical applications has been studied, but there is insufficient data for conclusions about safety and efficacy. Short-term use increases minor adverse affects, but does not appear to increase major adverse effects. Long-term effects of cannabis are not clear, and there are safety concerns including memory and cognition problems, risk for dependence and the risk...